Method and apparatus for pressing a rotating roll against a surface

ABSTRACT

An ice cushion is used to press a rotating roll against a workpiece surface by hydraulic pressure, the ice preventing leakage of the underlying water between the roll and adjacent guide walls.

United States Patent 1 1 3,592,036

[72] inventor PaulBlain [Sl] lnt.Cl. B2lb3l/32 Saint German-en-Laye. France {50] Field ofSearch.... 72/199. [21] AppLNo. 841,949 20l.237.24l.245.366; 308/188; l62/358; [22] Filed July 15,1969 l00/l70, 92, 38; 18/2 C [45] Patented July 13, I971 [73] Assignee Institut de Recherches de la Siderurgie 1 References Cited Francalse UNITED STATES PATENTS Sail" cermflwn-baye' France 3,03l,872 5/1962 Kusters 100/170 Priority J y 23,1968 3,120,174 2/1964 Ainsworth 100/170 1 Fran" 3,l46,l60 8/1964 Kankaanpaa 100/170 [3!] 160174 Primary E.raminer-R1chard J. l-lerbst Attorney-Kurt Kelman [54] METHOD AND APPARATUS FOR PRESSING A :EI? SURFACE ABSTRACT: An ice cushion is used to press a rotating roll raw against a workpiece surface by hydraulic pressure, the ice [52] U.S. Cl. 72/245, preventing leakage of the underlying water between the roll 100/170, 72/366 and adjacent guide walls.

PATENTED JUL] 3197: 3,592 O36 sum 2 OF 4 I is 2 i I 7c 7d a\ Qb l: I A;

RN V" INVEN OR PAUL BLA/N 41/1 MvEN T PATENIED Jun 3 IBM SHEET 3 OF 4 METHOD AND APPARATUS FOR PRESSING A ROTATING ROLL AGAINST A SURFACE BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to a method and apparatus for uniformly pressing a rotating cylinder against a surface, such as a working roll in a rolling mill or a papermaking machine, a calender, etc.

Working cylinders of this type must be so supported that they effect a uniform and regular pressure against the surface of the workpiece along their entire length. More particularly, in rolling mills for extra-thin metal strips, such as steel strips of several hundredths of a millimeter thickness, the roll must exert a uniform pressure against the strip along its entire width during the entire rolling operation, despite flexure of the roll, if a truly flat and nondeformed strip is to be obtained.

To obtain a uniform distribution of the pressure exerted by a rotating cylinder upon a workpiece, it has been proposed to use a cylinder having a diameter which is relatively small in relation to its length and thus to impart to the cylinder a certain flexibility in respect to the thickness of the workpiece, and to press the cylinder against the workpiece along its entire length by a fluid under pressure. Accordingly, the cylinder is arranged between two walls defining a recess and is rotatable therebetween about its axis. The recess is closed by the cylinder and is filled with a liquid under pressure. In practice, this has involved considerable difficulties because of leakage between the rotating cylinder and the wall of the recess. Since it is generally necessary to work with high pressures of the order of I to 300 bars (750 mm. Hg. the sealing problems are very difficult and liquid losses due to leakage are prohibitively high.

It is the primary object of the present invention to overcome these difficulties and to provide a method and apparatus for uniformly pressing a rotating cylinder against the surface of a workpiece without substantial loss of liquid between the cylinder and adjacent guide walls between which the cylinder is rotated.

This and other objects of this invention are accomplished by pressing the cylinder against the surface with a congealable liquid under pressure, and continuously cooling the space between the cylinder and the guide walls to congeal the liquid at least in this space. The surface of the rotating cylinder glides over the congealed liquid whereby leakage of liquid between the cylinder and the guide walls is prevented.

The apparatus of the invention comprises guide walls for the cylinder and means for rotatably supporting the cylinder between the guide walls. The guide walls and cylinder define a recess closed by the cylinder. A source of liquid under pressure is connected to the recess for supplying the liquid under pressure to the recess and pressing the cylinder against the surface. Means for cooling the liquid in the recess sufficiently congeals at least a portion of the liquid in the space between the guide walls and the cylinder to form a seal of congealed liquid in the space.

Such a system greatly facilitates the operation of a hydraulic support for working cylinders, such as otherwise conventional rolls in rolling mills. To roll very thin metal strips, a working roll of very small diameter must be pressed against the strip in a rigorously uniform manner. If hydraulic pressure is used for this purpose, the congealed liquid seals of this invention are very effective because the congealed liquid has a small friction coefficient with the metal in its solid state and because the hydraulic fluid used to press the roll against the strip serves itself as a seal in its congealed portions. Water has all the necessary properties for this purpose and is, therefore, preferred although other congealable liquids of like properties may obviously be used.

BRIEF DESCRIPTION OF DRAWING The above and other objects, advantages and features of the present invention will become more apparent from the following detailed description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawing wherein FIG. 1 is a transverse section of a support for a roll of a rolling mill for extra-thin metal strips according to one embodiment of this invention;

FIG. 2 is a similar view ofanother embodiment;

FIGS. 3 and 4 are longitudinal side elevations, partly in section, of the embodiments of FIGS. 1 and 2, respectively; and

FIGS. 5 and 6 are sectional views similar to those of FIGS. 1 and 2 of two additional embodiments.

DETAILED DESCRIPTION FIGS. 1 and 3 are partial views ofa rolling mill for extra-thin metal strips, showing only those parts of the mills directly relevant to the present invention. The strip 1 is inserted and rolled between the two working rolls 2 and 3, where between it is subjected to pressure to reduce its thickness. The working roll 2 is supported freely movably in a direction transverse to the strip 1 so that it may be moved upwardly and pressed against roll 3 by a cushion of ice 4. The axle of the working roll 3 is fixed and the diameter of this roll is far in excess of the diameter of roll 2. For practical purposes, the roll 3 may be considered as indeformable while the roll 2 is flexible and elastic, its diameter being small in respect to its length. For instance, the diameter of roll 2 may be of the order of 30 to 50 mm. for a strip width of300 to 600 mm.

Since ice is relatively plastic, the ice cushion 4 fully and uniformly transmits to the working roll 2 the pressure of the congealable fluid delivered under pressure through conduits 5 and inlets 6 into the bottom of the recess defined between the guide walls 7a, 7b, the roll 2, and end walls 7c, 7d. Therefore, the pressure to which the roll 2 is subjected is uniform throughout its length and, therefore, along the entire width of the metal strip 1 which is being rolled. On the other hand, any pressures exerted by different points on the strip being worked are distributed over the entire mass of the ice cushion and the length of the roll.

Thus, the working roll 2 may eliminate all irregularities in the strip and exerts a uniform pressure distributed over its entire working generatrix, thus producing a uniform reduction in the thickness of the strip along its entire width and an entirely flat strip impossible or, at least very difficult to obtain by conventional systems.

As will be seen in FIG. 1, the guide walls and 7b are mounted in rigid steel support 8 and their upper edges serve to guide the rotary roll 2 therebetween, the walls defining a recess whose top is closed by roll 2. In accordance with a preferred feature of the invention, the guide walls are made of a good thermal conductor material such as aluminum or copper. Copper is preferred. Under the hydraulic pressure of the congealable liquid supplied to the recess, the guide walls are strongly held in the support 8 which, in turn, is carried by a beam 9 which forms part of the amount for the cage of the rolling mill. The working roll 3 is pressed against the strip 1 by any conventional means exerting pressure on the bearings for the roll (not shown), none of this structure forming part of the present invention.

Cooling means for the liquid in the recess is provided in the guide walls 70, 7b for the constant removal of heat from the liquid or ice in cushion 4. The illustrated cooling means consists of a series of conduits 10a, 10b, in contact with the copper linings 7a, 7b. A refrigerant fluid, such as Freon (dichlorodifluoromethane), is circulated through the colling conduits from a source (not shown). The entire cooling system is protected from external heat by an insulating cover ll disposed about steel support 8. A further insulation is provided by a Teflon lining 12 between the copper guide walls 7a, 7b and their support 8.

The operation of this apparatus will be evident from the above description and proceeds as follows:

Water is pumped into the recess between the walls 7a, 7b through conduits under a pressure of 100 to 300 bars, and is distributed in the recess through the ports 6 at the bottom of the recess. Upon circulation of refrigerant through the conduits a, 10b, 10c, the water in the recess is cooled to ice and this ice cushion is pressed uniformly against the roll 2 under the pressure of the water coming up through inlet ports 6. The cooling may be so controlled that almost all the water in the recess is congealed into an ice cushion, leaving only a little liquid water at the bottom of the recess near the inlets 6. Thus, if the thermal equilibrium is momentarily unbalanced, for instance by a sudden increase in the temperature of the strip 1 without a compensating increase in refrigeration, a little of the ice cushion 4 will melt without destroying the entire cushion and, most importantly, leaving the seal between the roll 2 and the edges of the guide walls 70, 7b. Actually, even if the ice cushion has been melted to a very large extent, any water tending to leak out between the ice cushion and the walls 7a, 7b will be immediately frozen when it contacts the cold walls which are always held at a temperature below the solidification temperature of the water under the operating pressure. Thus, the water can never leak out of the recess.

The water is pumped into conduits 5 at a temperature slightly above its freezing temperature at the operation pressure. This temperature is a little below 0 C. The water may be cooled in a heat exchanger (not shown) before it is pumped into the present apparatus.

Relatively little water is consumed in this apparatus. Actually, the water consumed corresponds to the ice liquefied by the friction of the small roll 2 and the pressure it exerts upon the ice cushion.

In the embodiments of FIGS. 2 and 4, like parts functioning in a like manner are indicated by the same reference numerals as in FIGS. 1 and 3 to avoid redundancy in the description. In this embodiment, the refrigerant circulating conduits 13a, 13b in the guide walls cool only the upper portions of these walls, the lower portions of the walls being cooled only by heat transfer through the copper. Accordingly, only the spaces 40 and 4b directly adjacent the roll 2 and the guide walls will be cooled sufficiently to form ice seals in these spaces. The lower portions of the recess will be filled with water at slightly higher temperature so that the lower portion of the roll 2 will be in contact with liquid water, rather than ice. Generally speaking, this type of water-and-ice cushion for roll 2 will function similarly to the one previously described but it has certain advantages thereover, particularly if a great deal of heat must be removed from the water to congeal portions thereof, which happens particularly at high-rolling speeds. In this case, the mass of ice to be maintained is much smaller so that it is not necessary to increase the refrigerant circulation prohibitively.

As will be seen clearly in FIG. 3, the small roll 2 has no bearings. It is rotated by the movement of the strip 1 and guided entirely by the ice cushion 4 between the guide walls 7a, 7b. It is cooled by cooled copper end walls 7c, 7d which are connected to walls 7a, 7b. If desired, the end walls may be separately cooled in the same manner as the guide walls, or they are cooled merely by connection to the walls 7a, 7b by virtue oftheir high-thermal conductivity.

The modification of FIG. 4 differs from that of FIG. 3 in that the roll 2 is supported on trunnions l4 mounted in bearing slots in support 8 for movement in relation to strip II.

In the embodiments of FIGS. 5 and 6, like parts functioning in a like manner have again been designated by the same reference numerals. The embodiment of FIG. 5 is particularly useful for working rolls 2 of a relatively large diameter. In this embodiment, the entire cushion 4 in contact wit the roll 2 is congealed.

Intermediate the guide walls 7a and 7b and at the bottom of the recess, a refrigerant conduit of triangular cross section traverses the recess to divide its lower portion into two branches 41c and dd. Each of these branches is supplied with water by a series of inlet ports 6a and 6b receiving water under pressure from conduits 5a and 527, respectively. The same refrigerant as is used for cooling walls 70, 7b may be circulated through conduit 15, thus assuring freezing of the water in the center of the cushion as well as along the guide walls.

In the embodiment of FIG. 6, the lower portion of the cushion is constricted. Thus, the cooling effect of the cold guide walls rapidly solidifies the water in the axial zone. When the water pushes up under pressure, as the ice rises progressively in the cushion, a film of water is introduced between the cushion and the lateral guide walls in the region where the walls are inclined, and this film of water is instantly solidified as it contacts the cold walls. This has the advantage that the rise of the cushion is facilitated, and no ice will stick to the walls.

While the invention has been described and illustrated in connection with certain now preferred embodiments, it will be clearly understood that many modification and variations may occur to those skilled in the art without departing from its scope.

Iclaim:

I. A method of uniformly pressing a rotating cylinder against the surface of a workpiece, the cylinder being rotated between guide walls, comprising the steps of pressing the cylinder against the surface with a congealable liquid under pressure, and continuously cooling the space between the cylinder and the guide walls to congeal the liquid at least in said space, the surface of the rotating cylinder gliding over the congealed liquid whereby leakage of liquid between the cylinder and the guide walls is prevented.

2. The method of claim 1, wherein the guide walls are cooled to congeal the liquid in contact with the guide walls at least in the space immediately adjacent the guide walls and the rotating cylinder.

3. The method of claim 1, wherein all the liquid in contact with the rotating cylinder is congealed to form a cushion of congealed liquid which is pressed against the cylinder by underlying liquid under pressure.

4. The method of claim 1, wherein the liquid is water, and the water is cooled to a temperature close to the freezing point of water before the water is introduced under pressure into the space between the guide walls and the cylinder.

5. An apparatus for uniformly pressing a rotating cylinder against the surface of a workpiece, comprising guide walls for the cylinder of the type of rolls or calenders, means for rotatably supporting the cylinder between the guide walls, a. the guide walls and cylinder defining a recess closed by the cylinder,

3. a source ofliquid under pressure,

4. means for connecting the recess to said source for supplying the liquid under pressure to said recess and pressing the cylinder against said surface, and

5. means for cooling the liquid in the recess sufficiently to congeal at least a portion of the liquid in the space between the guide walls and the cylinder to form a seal of congealed liquid in said space.

6. The apparatus of claim 5, wherein the cooling means is provided in the guide walls.

7. The apparatus of claim 6, wherein the cooling means comprises conduits in the guide walls for circulating a cooling medium therethrough.

8. The apparatus of claim 7, wherein the guide walls include a lining of a good thermal conductor material, the circulating conduits being provided in said lining.

9. The apparatus of claim 5, further comprising a thermal insulation around said recess. 

1. A method of uniformly pressing a rotating cylinder against the surface of a workpiece, the cylinder being rotated between guide walls, comprising the steps of pressing the cylinder against the surface with a congealable liquid under pressure, and continuously cooling the space between the cylinder and the guide walls to congeal the liquid at least in said space, the surface of the rotating cylinder gliding over the congealed liquid whereby leakage of liquid between the cylinder and the guide walls is prevented.
 2. The method of claim 1, wherein the guide walls are cooled to congeal the liquid in contact with the guide walls at least in the space immediately adjacent the guide walls and the rotating cylinder.
 2. means for rotatably supporting the cylinder between the guide walls, a. the guide walls and cylinder defining a Recess closed by the cylinder,
 3. a source of liquid under pressure,
 3. The method of claim 1, wherein all the liquid in contact with the rotating cylinder is congealed to form a cushion of congealed liquid which is pressed against the cylinder by underlying liquid under pressure.
 4. The method of claim 1, wherein the liquid is water, and the water is cooled to a temperature close to the freezing point of water before the water is introduced under pressure into the space between the guide walls and the cylinder.
 4. means for connecting the recess to said source for supplying the liquid under pressure to said recess and pressing the cylinder against said surface, and
 5. means for cooling the liquid in the recess sufficiently to congeal at least a portion of the liquid in the space between the guide walls and the cylinder to form a seal of congealed liquid in said space.
 5. An apparatus for uniformly pressing a rotating cylinder against the surface of a workpiece, comprising
 6. The apparatus of claim 5, wherein the cooling means is provided in the guide walls.
 7. The apparatus of claim 6, wherein the cooling means comprises conduits in the guide walls for circulating a cooling medium therethrough.
 8. The apparatus of claim 7, wherein the guide walls include a lining of a good thermal conductor material, the circulating conduits being provided in said lining.
 9. The apparatus of claim 5, further comprising a thermal insulation around said recess. 